In electronics applications it is common to generate a desired clock signal at a frequency that is referenced to the frequency of a reference signal generated by a MRO (master reference oscillator). Phase locked loop (PLL) oscillators may be used for this purpose if there is a coherent phase relationship between the clock signal and the reference signal. Sometimes, however, the clock signal generator may be of a class wherein the clock signal must be synchronized to an incoherent stimulus, and then frequency locked oscillators may be used. There is a need for high performance frequency locked oscillators that can be embodied cheaply such as by using a semiconductor chip and a minimum of other component(s). Phase and/or frequency locked oscillator designs often include filters that have relatively long time constants. Thus, there is a further need for filters having long time constants, and that can be embodied cheaply, for example, by using a semiconductor chip and a minimum of other component(s).